Adaptive Selection of Transmission Neutralizer Pedal Setpoint

ABSTRACT

An automatic transmission neutralizer system for a machine is disclosed. The system may comprise at least one sensor configured to detect a set of parameters of the machine, a transmission, and a control unit operatively in communication with the at least one sensor and the transmission. The control unit may be configured to: calculate a braking force of the machine and an external force on the machine using the set of parameters detected by the at least one sensor, compare the braking force to the external force, and selectively neutralize the transmission depending on input from the at least one sensor and the comparison of braking force to external force.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to machines and, moreparticularly, to systems and methods for neutralizing transmission ofmachines.

BACKGROUND OF THE DISCLOSURE

Many machines used in earth-moving, industrial and agriculturalapplications have a transmission neutralizer feature that allows anoperator to manually control the neutralization or disengagement of thetransmission. Such machines include, but are not limited to, wheelloaders, track-type tractors, excavators, articulated trucks and thelike. With such systems, the operator may choose to neutralize thetransmission depending on the operating conditions and application ofthe brake pedal. For example, when operating on level ground, theoperator may neutralize the transmission early in the brake application.While operating on a slope, the operator may choose to neutralize thetransmission deeper into the brake application to prevent rollback ofthe machine.

On conventional machines, there are multiple push buttons that theoperator must toggle through in order to neutralize the transmission.Controlling the transmission with multiple push buttons not onlyrequires operators with high skill levels, but also requires theoperator to repeatedly switch modes of the transmission duringoperation. Given that operators have several other tasks to perform andmechanisms to control while operating the machine, the operators maybecome fatigued, overburdened, or frustrated due to the complexity ofthe controls. Furthermore, because the manual control settings of thetransmission neutralizer require the hands of the operators to travelfrom one push button to another, there is an inherent reaction timedelay.

Thus, there exists a need for an improved, reliable and efficient systemand method for neutralizing transmissions in such machines. U.S.pre-grant publication 2009/0132134 A1 discloses an inch/brake device fora transmission having a control system that uses brake pedal positionand accelerator pedal position as inputs. U.S.2009/0132134 A1 disclosesa first range of motion of the inch/brake device providing atransmission engagement force and a second range of motion providing abraking force. U.S.2009/0132134 A1 further discloses an acceleratormoving between two or more positions, wherein moving the acceleratorcauses an overlap between the first range of motion and the second rangeof motion to vary. However, U.S.2009/0132134 A1 does not disclosecontrolling a transmission by calculating outside forces acting on themachine.

SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure is directed to an automatictransmission neutralizer system for a machine. The system may include atleast one sensor configured to detect a set of parameters of themachine, a transmission, and a control unit operatively in communicationwith the at least one sensor and the transmission. The control unit maybe configured to: calculate a braking force of the machine and anexternal force on the machine using the set of parameters detected bythe at least one sensor, compare the braking force to the externalforce, and selectively neutralize the transmission depending on inputfrom the at least one sensor and the comparison of braking force toexternal force.

Another aspect of the present is directed to a machine having anautomatic transmission neutralizer system. The machine may comprise abrake pedal having a brake pedal sensor configured to detect an angle ofdepression of the brake pedal; a torque converter having an input sensorand an output sensor, the input sensor configured to detect a speedgoing into the torque converter and the output sensor configured todetect a speed coming out of the torque converter; a transmission systemcomprising a transmission, a transmission shaft, and a transmissioncontrol module; a speed sensor configured to detect a speed of thetransmission shaft; and a control unit operatively in communication withthe brake pedal sensor, input sensor, output sensor, speed sensor, andtransmission control module. The control unit may be configured to:calculate a braking force of the machine using input from the brakepedal sensor; calculate a propulsion force of the machine using inputfrom the input sensor and the output sensor of the torque converter;calculate an acceleration of the machine using input from the speedsensor; calculate an external force on the machine as a function of thebraking force, the propulsion force of the machine, a mass and theacceleration of the machine; compare the braking force to the externalforce; and output a signal to the transmission control module toselectively disengage the transmission based on input from the brakepedal sensor and the comparison of the braking force to the externalforce.

Another aspect of the present disclosure is directed to a transmissionneutralizer system for a machine. The machine may include a transmissionand a brake pedal having a brake pedal sensor configured to detect aposition of the brake pedal. The transmission neutralizer system mayinclude a transmission control module configured to disengage thetransmission, and a control unit in communication with the transmissioncontrol module and the brake pedal sensor. The control unit may beconfigured to: calculate a braking force and an external force; comparethe braking force to the external force; and send a signal to thetransmission control module to disengage the transmission based on inputfrom the brake pedal sensor and the comparison of the braking force tothe external force.

Another aspect of the present disclosure is directed to a method ofneutralizing a transmission of a machine is disclosed. The method mayinclude monitoring a brake pedal position; calculating an external forceon the machine; comparing the braking force to the external force; andselectively neutralizing the transmission according to the brake pedalposition and comparison of the braking force to the external force.

These and other aspects and features of the invention will become morereadily apparent upon reading the following detailed description whentaken in conjunction with the accompanying drawings.

Although various features are disclosed in relation to specificexemplary embodiments, it is understood that the various features may becombined with each other, or used alone, with any of the variousexemplary embodiments of the invention without departing from the scopeof the claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a machine according to an exemplaryembodiment of the present disclosure;

FIG. 2 is a block diagram of an exemplary automatic transmissionneutralizer system of the present disclosure;

FIG. 3 is an exemplary free body diagram of the machine of FIG. 1;

FIG. 4 is a logic diagram outlining exemplary logic in an automatictransmission neutralizer system according to the present disclosure; and

FIG. 5 is a flowchart outlining a method of neutralizing a transmissionaccording to the present disclosure;

While the present disclosure is susceptible to various modifications andalternative constructions, certain illustrative embodiments thereof willbe shown and described below in detail. The invention is not limited tothe specific embodiments disclosed, but instead includes allmodifications, alternative constructions, and equivalents thereof.

DETAILED DESCRIPTION

Reference will now be made in detail to specific embodiments orfeatures, examples of which are illustrated in the accompanyingdrawings. Generally, corresponding reference numbers will be usedthroughout the drawings to refer to the same or corresponding parts.

Turning now to FIGS. 1 and 2, an automatic transmission neutralizersystem 10 of a machine 12 is shown, according to an exemplary embodimentof the present disclosure. Although the machine 12 is shown to be awheel loader, it will be understood that in other embodiments, themachine may be any other type of machine or vehicle, used inearth-moving, industrial or agricultural applications, that utilizes atransmission neutralizer system. For example, the machine 12 may be, butnot be limited to, a wheel loader, a track-type tractor, a motor grader,an excavator, an articulated truck, a pipelayer, a backhoe, or the like.It is also to be understood that the machine 12 is shown mainly forillustrative purposes to assist in disclosing features of variousembodiments of the invention, but that FIG. 1 does not depict all of thecomponents of an exemplary machine.

That being said, the machine 12 may include an engine 13, a transmissionsystem 14, a control unit 16 for controlling the machine 12, a brakepedal 18, and a torque converter 20. The transmission system 14 maycomprise a transmission 22, a transmission shaft 24, and a transmissioncontrol module 26 for controlling the transmission 22. The control unit16 may be in communication with the transmission control module 22 andat least one sensor, such as, but not limited to, a brake pedal sensor28 configured to detect an angle of depression of the brake pedal 18, aspeed sensor 30 configured to detect a speed of the transmission shaft24, an input sensor 32 configured to detect a speed going into thetorque converter 20, and an output sensor 34 configured to detect aspeed coming out of the torque converter 20.

Turning now to FIG. 3, an exemplary free body diagram of the forces onthe machine 12 are depicted, wherein Fb denotes the braking force, Fedenotes the external force, and Fp denotes the propulsion force.Although the free body diagram depicts the machine 12 on a grade orslope, it will be understood that the diagram may apply to any conditionor environment in which the machine 12 is operating. As shown in FIG. 3,the direction of positive motion is represented by arrow 38. Thedirection of acceleration a and velocity v of the machine 12 are alsodepicted by their respective arrows. The braking force Fb is the forceexerted on the machine 12 by the brakes of the machine. The externalforce Fe is the force acting against the machine 12, such as,contributions from grade and rolling resistance. The propulsion force Fpis the force created by the machine 12 to propel the machine 12, such asthat caused by the engine 13 of the machine 12.

According to one exemplary embodiment of the present disclosure, thetransmission 22 of the machine 12 may be disengaged or neutralized whenthe braking force Fb is greater than or equal to the external force Fe.The braking force Fb of the machine 12 may be calculated by firstdetermining a brake pressure of the brake system of the machine. One waythe brake pressure may be determined is by the position of the brakepedal 18. Specifically, the brake pedal sensor 28 may detect the angleof depression of the brake pedal 18 and send a corresponding signal tothe control unit 16. Based on data programmed into the control unit 16regarding the approximate brake pressure that correlates to the angle ofdepression of the brake pedal 18, the control unit 16 may then estimatethe brake pressure. Another way the brake pressure may be determined isby directly detecting the brake pressure via a brake pressure sensor(not shown) which may be in communication with the control unit 16. Thebrake pressure sensor may detect the brake pressure by measuring ahydraulic oil pressure of the brake system and may send a correspondingsignal to the control unit 16. After the brake pressure is determined,the control unit 16 may calculate the braking force Fb based oncharacteristics of the brake system and dimensions of the moving partsof the machine 12. For example, the control unit 16 may use programmeddata relating to the brake disc area, clutch dimensions, tire radius,gear reduction ratios, or other parameters, to calculate the brakingforce Fb from the determined brake pressure.

From the free body diagram shown in FIG. 3, it can be seen that thesummation of all the forces on the machine 12 must equal the mass of themachine 12 multiplied by its acceleration, shown in the followingformula below:

ΣF=m·a

The summation of all the forces includes the braking force Fb, externalforce Fe, and propulsion force Fp, and substituting these forces intothe above equation results in the following equation:

Fb+Fe+Fp=m·a

After manipulating the above equation to solve for the external forceFe, the following formula results:

Fe=m·a−Fb−Fp

The control unit 16 may use the above formula to calculate the externalforce Fe on the machine 12. The calculation of braking force Fbdescribed above may be used in the formula for external force Fe. Tocalculate the propulsion force Fp of the machine, the input sensor 32and output sensor 34 of the torque converter 20 may send signalscorresponding to the torque converter 20 input speed and output speed,respectively, to the control unit 16. Using these signals, as well asknown torque converter 20 properties, what gear the transmission 22 ofthe machine 12 is in, associated gear reduction ratios of the machine,the tire radius, or other parameters of the machine 12 programmed intothe control unit 16, the control unit 16 may then calculate thepropulsion force Fp. For the m·a calculation, the known mass of themachine 12 may be programmed into the control unit 16, while theacceleration of the machine 12 may be determined from inputs provided bythe speed sensor 30. More specifically, the speed sensor 30 may detectthe rotational speed of the transmission shaft 24 and send acorresponding signal to the control unit 16. The control unit 16 maythen determine the speed of the machine 12 based on the rotational speedof the transmission shaft 24 and the dimensions of the moving parts ofthe machine 12, such as the tire radius and gear reduction ratios. Next,the control unit 15 may calculate the acceleration of the machine 12, orthe derivative of the speed of the machine 12, by monitoring the rate atwhich such speed is changing.

It will be understood that although the system and method describedabove for calculating braking force Fb and external force Fe has beendisclosed herein, other systems and methods may be used withoutdeparting from the scope of the invention. For example, according to yetanother embodiment of the present disclosure, an inclinometer may beused to determine the grade or angle of inclination on which the machine12 is operating. The inclinometer (not shown) may be in communicationwith the control unit 16, which may then use the measured angle inputfrom the inclinometer, as well as the known mass of the machine 12 andacceleration of gravity to calculate the external force Fe.

After calculating the braking force Fb of the machine 12 and theexternal force Fe on the machine 12 as described above, the control unit16 compares the braking force Fb to the external force Fe. If thebraking force Fb is equal to or greater than the external force Fe, thenthe control unit 16 may output a signal to disengage or neutralize thetransmission 22. More specifically, the control unit 16 may send asignal to the transmission control module 26, which may then put thetransmission 22 into neutral.

Turning now to FIGS. 4 and 5, an exemplary logic diagram for thetransmission neutralizer system 10 and associated flowchart of anexemplary method are shown, respectively, according to anotherembodiment of the present disclosure. The logic illustrated in FIG. 4may be programmed into the control unit 16 of the machine 12. As shownat first step 62 (see FIG. 5), the brake pedal sensor 28 may detect theposition or angle of depression of the brake pedal 18. As describedabove, the control unit 16 may then calculate the braking force Fb fromthe detected angle of depression of the brake pedal 18. Next at step 64,and as shown by comparator 42 (FIG. 4), the control unit 16 may comparethe detected brake pedal position to a minimum brake pedal position orminimum angle of depression of the brake pedal 18 that is programmedinto the control unit 16 to ensure that there is sufficient applicationof the brake pedal 18.

At step 66, and as shown by comparator 44, if the minimum brake pedalposition is met, then the control unit 16 may compare the detected brakepedal position to a maximum brake pedal position or maximum angle ofdepression of the brake pedal 18, which may be programmed into thecontrol unit 16. If the maximum brake pedal position is met, then thecontrol unit 16 may output a signal to neutralize the transmission 22.In this case, the transmission would be neutralized regardless of theexternal force because of the significant application of the brake pedal18.

At step 68, and as shown by gate 46, if there is sufficient applicationof the brake pedal 18 but the maximum brake pedal position has not beenmet, then the control unit 16 may determine whether the machine 12 ismoving below a threshold speed. More specifically, the control unit 16may compare the machine 12 speed, which can be determined based on inputfrom the speed sensor 30 (as described above), to a threshold speed thatmay be programmed into the control unit 16. If the machine is not movingbelow the threshold speed, then at step 70, the control unit 16calculates the external force Fe, as described in detail above. However,if the machine 12 is moving below the threshold speed, then at step 72,the control unit 16 may latch or hold the last known calculation forexternal force Fe for the following process (step 74) of comparing thebraking force Fb to external force Fe. At low speeds, the detected orcalculated parameters may become less accurate due to friction or othercircumstances. Thus, the control unit 16 may compensate for this byusing the last known or most recent calculation of external force Feonce the machine 12 operates below the threshold speed.

At step 74, and as shown by comparator 48, the control unit 16 comparesthe braking force Fb to the external force Fe. If the braking force Fbis greater than or equal to the external force Fe, then the control unit16 may output a signal to neutralize the transmission 22 (at step 76)because there is sufficient braking force Fb to prevent roll back of themachine 12. If the braking force Fb is less than the external force Fe,then the transmission 22 is not disengaged.

It will be understood that although the steps 62-76 of the method shownin the flowchart of FIG. 5 are shown and described as being successive,the control unit 16 may perform the processes outlined in the method andlogic diagram in parallel without departing from the scope of thepresent disclosure. The flowchart in FIG. 5 is shown and described forexemplary purposes only to assist in disclosing the various features ofthe transmission neutralizer logic depicted in FIG. 4.

INDUSTRIAL APPLICABILITY

In general, the foregoing disclosure finds utility in various industrialapplications, such as in earth-moving, industrial, construction andagricultural machines. In particular, the disclosed transmissionneutralizer system and method may be applied to wheel loaders, and thelike. By applying this system and method to a machine, such as a wheelloader, automatic neutralization of a transmission can be achieved.Furthermore, the automatic transmission neutralizer system and methoddisclosed herein provides for adaptive selection of the transmissionneutralizer setpoint. Thus, the present invention adapts theneutralization setpoint to the operating conditions of the machine,thereby resulting in a reliable and efficient system and method forneutralizing transmissions, while eliminating the need for an operatorof the machine to manually select control settings in order toneutralize the transmission during operation.

While the foregoing detailed description has been given and providedwith respect to certain specific embodiments, it is to be understoodthat the scope of the disclosure should not be limited to suchembodiments, but that the same are provided simply for enablement andbest mode purposes. The breadth and spirit of the present disclosure isbroader than the embodiments specifically disclosed and encompassedwithin the claims appended hereto.

While some features are described in conjunction with certain specificembodiments of the invention, these features are not limited to use withonly the embodiment with which they are described, but instead may beused together with or separate from, other features disclosed inconjunction with alternate embodiments of the invention.

What is claimed is:
 1. An automatic transmission neutralizer system fora machine, comprising: at least one sensor configured to detect a set ofparameters of the machine; a transmission; and a control unitoperatively in communication with the at least one sensor and thetransmission, the control unit configured to: calculate a braking forceof the machine and an external force on the machine using the set ofparameters detected by the at least one sensor; compare the brakingforce to the external force; and selectively neutralize the transmissiondepending on input from the at least one sensor and the comparison ofbraking force to external force.
 2. The system of claim 1, wherein thecontrol unit is configured to neutralize the transmission if the brakingforce is greater than or equal to the external force and a minimum brakepedal position is met.
 3. The system of claim 2, wherein the controlunit is configured to also neutralize the transmission if a maximumbrake pedal position is met.
 4. The system of claim 3, wherein thecontrol unit is configured to compare the braking force to a last knowncalculation for external force if the machine is moving below athreshold speed.
 5. The system of claim 1, wherein the control unitcalculates the external force on the machine as a function of thebraking force, a propulsion force of the machine, a mass and anacceleration of the machine.
 6. The system of claim 1, wherein the atleast one sensor comprises a brake pedal sensor, and wherein the controlunit is configured to calculate the braking force of the machine usinginput from the brake pedal sensor.
 7. The system of claim 6, wherein thebrake pedal sensor is configured to detect an angle of depression of abrake pedal of the machine, and wherein the control unit is configuredto approximate a brake pressure based on the angle of depression and tocalculate the braking force from the brake pressure and a set of knownparameters programmed into the control unit.
 8. The system of claim 1,wherein the at least one sensor comprises a brake pressure sensor, andwherein the control unit is configured to calculate the braking force ofthe machine using input from the brake pressure sensor.
 9. The system ofclaim 8, wherein the brake pressure sensor is configured to detect abrake pressure by measuring a hydraulic oil pressure of a brake systemof the machine, and wherein the control unit is configured to calculatethe braking force from the brake pressure and a set of known parametersprogrammed into the control unit.
 10. The system of claim 5, furthercomprising a torque converter having an input sensor and an outputsensor, and wherein the control unit is configured to calculate thepropulsion force using input from the input sensor and output sensor ofthe torque converter.
 11. The system of claim 5, wherein the at leastone sensor further comprises a speed sensor configured to detect a speedof a transmission shaft, and wherein the control unit is configured tocalculate the speed and acceleration of the machine using input from thespeed sensor.
 12. The system of claim 1, further comprising atransmission control module, the transmission control module configuredto neutralize the transmission based on input from the control unit. 13.The system of claim 1, further comprising an inclinometer, and whereinthe control unit is configured to calculate the external force usinginput from the inclinometer.
 14. A machine comprising: a brake pedalhaving a brake pedal sensor configured to detect an angle of depressionof the brake pedal; a torque converter having an input sensor and anoutput sensor, the input sensor configured to detect a speed going intothe torque converter and the output sensor configured to detect a speedcoming out of the torque converter; a transmission system comprising atransmission, a transmission shaft, and a transmission control module; aspeed sensor configured to detect a speed of the transmission shaft; anda control unit operatively in communication with the brake pedal sensor,input sensor, output sensor, speed sensor, and transmission controlmodule, the control unit configured to: calculate a braking force of themachine using input from the brake pedal sensor; calculate a propulsionforce of the machine using input from the input sensor and the outputsensor of the torque converter; calculate an acceleration of the machineusing input from the speed sensor; calculate an external force on themachine as a function of the braking force, the propulsion force of themachine, a mass and the acceleration of the machine; compare the brakingforce to the external force; and output a signal to the transmissioncontrol module to selectively disengage the transmission based on inputfrom the brake pedal sensor and the comparison of the braking force tothe external force.
 15. The machine of claim 14, wherein the controlunit outputs a signal to the transmission control module to disengagethe transmission if either a maximum pedal position is met, or a minimumpedal position is met and the braking force is greater than or equal tothe external force.
 16. The machine of claim 15, wherein the controlunit is configured to compare the braking force to a last knowncalculation for external force if the machine is moving below athreshold speed.
 17. A transmission neutralizer system for a machine,the machine comprising a transmission and a brake pedal having a brakepedal sensor configured to detect a position of the brake pedal, thetransmission neutralizer system comprising: a transmission controlmodule configured to disengage the transmission; and a control unit incommunication with the transmission control module and the brake pedalsensor, the control unit configured to: calculate a braking force and anexternal force; compare the braking force to the external force; andsend a signal to the transmission control module to disengage thetransmission based on input from the brake pedal sensor and thecomparison of the braking force to the external force.
 18. The system ofclaim 17, wherein the machine further comprises an inclinometer, andwherein the control unit is in communication with the inclinometer andis configured to calculate the external force based on input from theinclinometer.
 19. The system of claim 17, wherein the control unit isconfigured to calculate the braking force using input from the brakepedal sensor.
 20. The system of claim 17, wherein the machine furthercomprises a brake pressure sensor configured to detect a brake pressure,and wherein the control unit is configured to calculate the brakingforce using input from the brake pressure sensor.
 21. The system ofclaim 17, wherein the machine further comprises a speed sensor and atorque converter having an input sensor and an output sensor, andwherein the control unit is in communication with the speed sensor,input sensor and output sensor and is configured to calculate theexternal force using the braking force calculation and input from thespeed sensor, input sensor and output sensor.
 22. A method ofneutralizing a transmission of a machine, comprising: monitoring a brakepedal position; calculating a braking force of the machine and anexternal force on the machine; comparing the braking force to theexternal force; and selectively neutralizing the transmission accordingto the brake pedal position and comparison of the braking force to theexternal force.
 23. The method of claim 22, further comprising comparingthe braking force to a most recent calculation for external force whenthe machine is moving below a threshold speed.